Fluid circuits for temperature control in a thermal therapy system

ABSTRACT

A system and method for fluid control in a thermal therapy system is disclosed. A fluid circuit permits passage of a fluid through a fluid circuit, including into and out of a treatment zone so as to cool or heat or maintain a temperature in said treatment zone at or near a desired temperature. The temperature is sensed at a point in the circuit between a discharge of a fluid pump and the treatment zone. MRI based thermometry of tissue in the treatment zone is accomplished in some aspects. Furthermore, a desired temperature may be programmably set to a given value or within a band of values using a processor and a temperature controller. In some aspects, leakage of fluid from a patient or from the fluid control system is captured by a leak-proof member to protect imaging and treatment equipment from damage.

RELATED APPLICATIONS

The present application is related to and claims priority under 35 USC§120 to U.S. Provisional Application No. 61/311,837, bearing the presenttitle, filed on Mar. 9, 2010, which is hereby incorporated by reference.

TECHNICAL FIELD

The present application relates to ultrasound therapy systems, andparticularly to ways for controlling a temperature (e.g., cooling) of athermal therapy applicator and/or the regions of tissue proximal to thesame within a patient undergoing thermal therapy such as ultrasoundthermal therapy.

BACKGROUND

Ultrasonic transducers have been employed in ultrasound therapy systemsto achieve therapeutic heating of diseased and other tissues. Arrays ofultrasound transducers operating to form a beam of ultrasonic energycause a conversion of sound to thermal energy in the affected tissueareas or treatment volumes, and a subsequent beneficial rise in thetemperature in the treatment volumes. With proper monitoring of theheating effect, ultrasound therapy systems can be used to treat harmfulcells and to controllably destroy cancerous tumors.

As known to those skilled in the art, ultrasonic transducers areconstructed and operated to take electrical power and produce ultrasoundenergy waves from a surface of a transducer element in a processgenerally referred to as transduction. The nature and extent of thetransduction depends on the material used to construct the transducers,transducer geometry, and the electrical input to the transducers. Acommon material used in construction of ultrasound transducers ispiezo-electric transducer crystal material, e.g., lead zirconatetitanate (PZT).

One challenge in constructing clinically-usable systems for image-guidedtherapy is in constructing the electrical, mechanical, andelectro-mechanical support systems for providing thermal therapy to apatient. This is especially true if part of the system needs to residein an environment having strong magnetic fields such as is found inmagnetic resonance imaging (MRI) environments.

It is useful to have a controllable and sterile system for controlling atemperature of a therapy device in a patient during a thermal therapytreatment procedure.

SUMMARY

Embodiments hereof are directed to systems and methods for providing athermal therapy applicator and supporting components that is suitablefor ultrasonic thermal therapy treatments in an image-guided environmentsuch as in magnetic resonance imaging (MRI) environments.

Aspects of the present disclosure provide fluid handling loops suitablefor operation during image-guided thermal therapy and clinically sterilefor penetration into patients and patient treatment applicators.

One embodiment is directed to a fluid control system for use in athermal therapy system, the fluid control system comprising a volume forfilling with a fluid, said fluid adapted for flow through a fluidcircuit portion of said apparatus; a pressure source that drives saidfluid through said fluid circuit; an inlet portion of said fluid circuitthat allows said fluid to pass into a portion of said thermal therapysystem; an outlet portion of said fluid circuit that allows said fluidto pass out of said portion of said thermal therapy system; atemperature sensor that senses a temperature of said fluid, or atemperature of a patient's tissue proximal to a position of saidtemperature sensor, and provides a corresponding temperature sensoroutput signal indicative of said temperature; a temperature controllerthat receives said temperature sensor output signal and that receives areference signal indicative of a desired temperature setting, and thatprovides an output control signal; and a thermal element that receivessaid output control signal and that acts to change the quantity of heatenergy in the fluid so as to maintain the temperature of said fluidsubstantially at or near the desired temperature setting. Anotherembodiment is directed to a method for controlling a fluid in a thermaltherapy system, comprising providing a fluid in a fluid circuit; pumpingsaid fluid through an inlet portion of the fluid circuit to a locationproximal to which a temperature is to be controlled; receiving a returnof said fluid from said location into a return portion of said fluidcircuit; measuring a temperature of said fluid substantially at orproximal to said location and generating a temperature sensing signalcorresponding to said temperature; comparing said temperature sensingsignal to a reference signal; and controlling a heat element to add heatto said fluid if its temperature drops below a desired setting or toremove temperature from said fluid if its temperature rises above saiddesired setting.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, reference is be made to the following detailed description ofpreferred embodiments and in connection with the accompanying drawings,in which:

FIG. 1 illustrates an exemplary system for providing image-guidedultrasound therapy to a patient;

FIG. 2 illustrates an exemplary fluid processing system including aprimary and a secondary fluid circuit for controlling a temperature inand/or around a thermal therapy applicator;

FIG. 3 illustrates a schematic exemplary temperature control system; and

FIG. 4 illustrates a simplified fluid circuit with catchment member.

DETAILED DESCRIPTION

As discussed above, better understanding of the electrical response ofultrasound transducers in therapeutic systems is useful for improvingthe effectiveness of such systems and delivering safe efficienttreatment to patients.

FIG. 1 illustrates an exemplary system 10 for providing image-guidedultrasound therapy to a patient. The simplified illustration shows amaster computer 100, such as a portable PC, workstation, or otherprocessing device having a processor, memory, and coupled to someinput/output apparatus. Master computer 100 may include a display andmay support a user interface 110 to facilitate control of andobservation of the thermal therapy treatment process.

Master computer 100 is adapted for coupling to other systems andcomponents through a computer interface connector 120. Connection 120carries data and information to and from master computer 100 and maycomprise standard or special-purpose electrical wiring connectioncables, such as serial connection cables or the like. Also, connection120 may be achieved wirelessly as known to those skilled in the art ofwireless communication, and may further be achieved by way of multipleconnections, over a network, or by another suitable method.

In some embodiments, master computer 100 is coupled through connection120 to a power control unit 130. Power control unit 130 may beimplemented as a stand-alone hardware apparatus but may be implementedas a part of master computer 100, e.g., by being built onto a specialcard in a computer or server system that accommodates such hardwarecomponents.

Power control unit 130 may specifically include at least a processoradapted for processing machine or program instructions, which may beprovided to the processor from another component of system 10 and may bestored on a memory device in power control unit 130. Circuitry includinganalog and/or digital circuitry may be operated within power controlunit 130 so as to determine an output power to one or more ultrasoundtherapy transducer elements in an ultrasound therapy apparatus 150.

In some embodiments, power control unit 130 may deliver controlledelectrical driving signals to a plurality of ultrasound transducerelements (e.g., PZT array elements) in ultrasound therapy apparatus 150.The driving signals may be controlled to deliver a programmed amount ofpower to each element or to groups of elements of therapy apparatus 150.The driving signals may also be controlled so as to provide a determineddriving voltage, current, amplitude, waveform, or frequency to saidultrasonic transducers of therapy apparatus 150. Such electrical drivingsignals are carried from power control unit 130 to the ultrasoundtherapy apparatus 150 over suitable wires, cables, or buses 140.Appropriate plug interfaces or connectors may be included so as to matethe various ends of the connectors or buses to and from their associatedcomponents.

In operation, ultrasound therapy apparatus 150 includes a portion 155that is inserted into a portion of a patient's body to deliver asuitable dose of ultrasound energy to tissue in a diseased region of thepatient's body.

The patient and the ultrasound therapy apparatus 150 are generallydisposed in an imaging volume 160 such as a magnetic resonance imaging(MRI) apparatus, which can provide real-time images of the relevantparts of the patient, e.g., the treatment volume to master computer 100or display and user interface 110. In some embodiments, real-timemonitoring of the thermal therapy is performed so that a clinicaloperator can monitor the progress of the therapy within the treatmentvolume or diseased tissue. Manual or automated changes can be made tothe power signals from power control unit 130 based on input from theresults and progress of the treatment.

The feedback and coupling of the treatment system components to thecontrol components in system 10 can be used to ensure that an optimumradio frequency (RF) power signal is provided to each element of anultrasound array 155 used in treatment of diseased tissues. Someexamples include treatment of prostate cancer tumors in male patientsusing MRI guided ultrasound therapy applications.

RF power control unit 130 may include separate circuit cards havingindividual processors, amplifiers, filters and other components toachieve the desired driving power output to the elements of ultrasoundarray 155 of ultrasound treatment apparatus 150. Alternatively, a singleprocessor may be employed to control the behavior of the various powerchannels to each array element.

In the embodiments described below, a fluid system is used to controlthe temperature of the thermal therapy apparatus or applicator and/or tocontrol a temperature of a region of tissue proximal to the therapyapplicator.

FIG. 2 illustrates a system 20 for providing and controlling fluiddelivery to and from a thermal therapy applicator. The fluid may be usedto cool (or heat) various components of the thermal therapy applicator.The fluid may also cause the tissues adjacent to the applicatorapparatus to be affected so as to prevent unwanted overheating of aregion of healthy tissue directly proximal to an ultrasound applicator.

As is known to those skilled in the art, magnetic imaging environmentssuch as MRI environments are subjected to strong magnetic fields fromone or more magnets used in the MRI imager apparatus. For this reason,it is often difficult to have equipment within a MRI environment that isaffected by such strong magnetic fields. Therefore, pumps, motors,heaters, electronic systems, computers, and other electro-mechanicalapparatus are affected or even damaged by magnetic fields used in MRIenvironments.

Accordingly, MRI centers usually employ magnetic shielding walls,sometimes Faraday chambers or conductive sheathing, to shield theinterior of the MRI environment from the operational environment outsidethe MRI environment.

In FIG. 2 such a shielding wall 200 is shown that defines a magnetizedenvironment 204 within the magnetic (MRI) imaging chamber and anon-magnetized environment 202 that is outside, or shielded from, themagnetic environment. Computers and other electro-mechanical devices canbe used in the non-magnetized environment 202 because wall 200 shieldsenvironment 202 from the heavy magnetic fields and associated inductioncurrents present inside magnetized imaging environment 204. Inside themagnetized chamber 204, equipment should preferably be immune tomagnetic fields and induction currents. Equipment made of non-ferrous ornon-magnetizable components is usually able to operate normally withinmagnetic environments. Ceramic and plastic materials are examples ofmaterials that can be used to construct mechanical components for use insuch magnetic environments.

In operating systems requiring some components to be within themagnetized space 204 and others to be in non-magnetized space 202, apenetration panel 206 is provided to allow passage of electrical cablingand/or fluid tubing between the sides 204 and 202 of wall 200.

As is also known to those skilled in the art, magnetic imagingenvironments such as MRI environments may be disturbed by the presenceof electrical interference at or near the Larmor frequency. For thisreason, it is sometimes difficult to have electrical equipment within aMRI environment because it may adversely affect the detection of smallmagnetic fields that are used to generate the MR image. Therefore,pumps, motors, heaters, electronic systems, computers, and otherelectro-mechanical apparatus can prevent the MRI from functioning asintended or may detract from the quality of its operation.

Upon examination of the fluid system of FIG. 2, it is apparent that twodistinct fluid loops are used to provide the instant temperaturecontrol. First, a “primary” fluid loop drawn near the bottom of FIG. 2is used to deliver fluid in a first fluid circuit into and then out of apatient's body by way of the thermal therapy applicator apparatus asdescribed in other applications by the present inventors and assignee.This primary fluid circuit controls the temperature of the apparatus andthe patient's tissue near the apparatus and the primary fluid circuitresides in components shown within the magnetized imaging and treatmentenvironment 204. Another fluid circuit, which may be denoted as a“secondary” fluid loop is used to control the temperature of the first“primary” fluid loop. In general, the fluid systems are used forcooling, or removal of heat energy from the therapy device and thepatient, but the present discussion is not so limiting. The secondaryfluid circuit extends into the upper non-magnetized space 202, where itcan be cooled by external means.

In operation, the primary fluid loop delivers cooling (or generallytemperature-control) fluid to the patient by way of the therapyapparatus through piping line or duct or tube 272. The return path ofthe primary fluid is through piping or ducting or tubing 270. Generally,in a cooling scenario, the temperature of the fluid entering the patientthrough line 272 is lower than the temperature of the fluid leaving thepatient through line 270. The amount of thermal energy being removed perunit time can be easily computed by knowing the difference intemperature between the fluid in lines 272 and 270 and knowing thevolumetric flow rate of the fluid therein. Because cooling fluids (e.g.,water, saline) are essentially incompressible, a fluid flow measuringdevice can be installed in one or both legs 272, 270 to measure andreport the primary fluid loop volumetric flow rate. Similarly,thermometric devices in legs 270 and 272 can be used to record andreport the temperature in the ingress and egress legs of the primaryfluid circuit.

The primary fluid circuit is preferably kept short and near thetreatment device and patient within chamber 204. This minimizes thefrictional “head loss” in the circuit and reduces the distance overwhich the primary cooling fluid needs to be transported duringoperation. In one respect, this simplifies the design and lowers thecost of the system.

A Sterile fluid pump 240 such as a peristaltic pump may be used to moveprimary cooling fluid through the primary fluid circuit. Thermal sensor250 records the measured temperature of the fluid and can provide aninput to a fluid pump controller circuit. A fluid fill and gas removalapparatus 260 is coupled to the primary fluid circuit to remove gas(e.g., air) bubbles from the circuit and to fill and maintain thecircuit. It is understood that other components such as sensors andfilters may also be included in the primary fluid circuit.

The heat collected by the fluid in the primary fluid circuit is cooledin a thermal transfer block heat exchanger 230, where the secondaryfluid removes the heat from the primary fluid without coming intocontact with it. Convoluted tubing or heat exchanger fins within thermaltransfer block 230 may be used to enhance the heat exchangecharacteristics of block 230. The temperature control system can apply atemperature modulation to set the temperature of the circulating fluidto a given setting or within a given temperature band (min, max) asdesired. In some embodiments, the temperature is monitored at one ormore locations in the fluid circuit, e.g. at a given location proximalto key patient organs, and the temperature modulation is designed toprotect such key organs from damage due to unwanted exposure to heatingor cooling during operation of the system.

Secondary fluid is moved using a fluid heater and pumping unit 210,which is controlled by a temperature control unit 220. The temperaturecontrol provides heating and/or cooling of the circulating fluid, forexample, heating the fluid if its temperature drops below a giventemperature due to heat loss to the environment where the fluid isstored and circulated, or, cooling the fluid if its temperature exceedsa given set point from exposure to ultrasound energy, heated tissue,electrical components, etc.

The pumping unit of 210 may include any known useful pumps, includingmagnetically driven motorized pumps, peristaltic pumps, displacement orreciprocating pumps and the like. The temperature control unit 220provides a signal to control the pumping of the secondary fluid withinthe secondary fluid loop, and in turn through thermal transfer block230. Again, calculation of the rate of thermal energy removal (oraddition) in the system overall can be computed by placement oftemperature sensors in the secondary flow loop and knowledge of thevolumetric flow rate therein.

The penetration panel 206 may include custom or standard fittings forpassage of the secondary fluid across the wall 200. The secondary fluiddoes not necessarily have to be sterile, and can be substantially longer(not shown to scale in the drawing) than the length of the primary fluidtubing. Continuous tubing may be passed through wall 200 to move thesecondary cooling fluid through wall penetrations in penetration panel206. Alternatively, separate tubing may be provided in the secondaryfluid loop for sides 202 and 204 so that fittings are used to connectthe inner (on side 204) and outer (on side 202) portions of thesecondary fluid loop as is described in related applications to thepresent assignee.

Either the primary or the secondary fluid flow loops may be used tocontrol the cooling or heating to the thermal therapy device andpatient, or a combination of both the primary and secondary loops may becontrolled together to achieve the optimal thermal energy movement to orfrom the therapy device and patient.

FIG. 3 illustrates an exemplary sterile fluid loop temperature controlsystem 30. A temperature control unit 300 includes circuitry andinstructions for accepting inputs and providing outputs including fortemperature control of the afore mentioned fluid circuit. A processor orcomputer CPU can process information as required and interfaces to othercomponents such as a temperature controller 310. Note that thetemperature controller 310 may be implemented as a single apparatusalong with the treatment control unit or as a separate circuit orcomponent as desired in a given application using separate or combinedhardware and software to accomplish the purpose of the system.

In some embodiments, the treatment control unit 300 acts on stored orinput data to determine a temperature setting desired at one or morelocations within the fluid loop. In one example, the temperature sensor320 is located proximal to a sensitive patient organ, e.g.neuro-vascular bundles, or other healthy tissues that are not to beover-heated or over-cooled.

In another embodiment, a temperature sensor e.g. 322 is located at a keylocation in the fluid circuit, for example at a discharge of a pump orin a fluid storage reservoir. The pump acts as a pressure source todrive the movement of the fluid through the system's fluid circuit. Thetreatment control unit 300 sends temperature control signals totemperature controller 310 so that temperature controller 310 can act tocontrol a heat input/output device 330 to maintain the temperature inthe fluid circuit or locations therein.

Temperature controller 310 is coupled to exchange signals with treatmentcontrol unit 300 as described above. Temperature controller 310 alsoreceives input signals from one or more temperature sensors, e.g., IRsensors, bimetallic sensors, thermocouples or other sensors, to measurethe temperature of the fluid at corresponding one or more locations.Temperature controller 310 also sends control signals to activate orcontrol the heat input/output device 330. The heat input/output device330 is meant to anticipate a heater element, heating coil, radiativeheater, or other means of adding heat to the fluid; or a cooler,chiller, or other means of removing heat from the fluid. Therefore, forthe present purposes, we can refer to heat input/output device 330generally (regardless of whether it is used for heating or cooling thefluid) because it causes the addition of heat, removal of heat, or boththe addition and removal of heat from the fluid. So in some embodimentsseparate heating and cooling elements are used, whereas in otherembodiments a single heat pump or other means can achieve both heatingand cooling as needed. In yet other embodiments a heater and a chillerare both used in series and one or both are controlled by thetemperature controller 310 as needed.

As said before, temperature controller 310 can act to keep fluid 340 ata set temperature as indicated by temperature control unit 300 in someembodiments. In other embodiments, a preset or programmed band oftemperatures sets a minimum and a maximum temperature range within whichfluid 340 is to be maintained. A pair of limit switches coupled tocorresponding sensors can be used to activate a heating or coolingcycle. The settings and ranges of temperatures desired can be based onavoiding unwanted thermal damage to areas of the patient such as hisreproductive, nervous, circulatory, or waste removal organs. In somespecific embodiments, the temperature setting or temperature band is setto maintain the fluid and/or the patient's tissue at a temperaturesubstantially similar to the body's normal internal temperature.

It can be appreciated by those skilled in the art that the presenttemperature control system 30 might also be used to promote certaintherapeutic effects. For example, if the location and nature of thepatient's disease is such that the therapy can benefit from localheating of the tissue in the treatment zone using the circulating fluidthen this can be accomplished. For example, the fluid in one part of thefluid circuit may be heated to a given temperature before or during thetherapy. However, this is not required in many preferred embodiments.

For the sake of further clarity, we describe next a preferred embodimenthereof. A patient having prostate cancer is presented for treatment. Theentire prostate, or diseased portions thereof, are to be treated using athermal therapy procedure. Treatment by hyperthermia from an array ofultrasound transducers electrically driven and electronically is apreferred embodiment. The ultrasound therapy applicator may be insertedinto the patient's urethra and up to a place within the treatment zonein the prostate, which surrounds the urethra. The ultrasonic elements ofthe array are driven in magnitude and waveform so as to cause depositionof ultrasound energy into the diseased tissue. The diseased tissue isthus heated and upon reaching a certain temperature and/or thermal dosethe cells of the diseased tissue (e.g., cancer cells) are destroyed.Fluid is circulated in the treatment apparatus as described above, saidcirculation of fluid moving in and out of the treatment zone proximal toan in the patient's body, and on to the rest of the circuit, which ispreferably kept sterile and at a known temperature or in a given rangeof temperatures at key locations in the circuit. In one specificpreferred embodiment, the temperature of the circulating fluid ismonitored just downstream of (near the discharge of) the pressure driver(pump). The temperature of the circulating fluid is maintained andmonitored thus by using a temperature sensor (e.g., infrared “IR”sensor) coupled to a temperature controller circuit. The temperaturecontroller circuit causes a thermal element (heater in one embodiment)to heat the fluid. In an aspect, the fluid may be heated by the thermalelement/heater and may cool by heat loss to the environment and othercomponents of the system. However, this is not limiting, and the fluidthermal element may cool the fluid as well if needed.

FIG. 4 illustrates a treatment environment 40 for treating a patient ofa disease using the aforementioned ultrasonic therapy systems andmethods. The patient 400 is supported on a table, platform, gurney, orother support member 410. In some embodiments the patient 400 is restingon his back substantially as shown, and may be further secured to thesupport platform 410 with straps or other cushions to limit his movementduring treatment and imaging and to provide a safe and comfortableresting place for the patient.

A fluid is circulated into and out of the treatment apparatus asdescribed earlier, and is simplistically represented here as an incomingfluid stream 440 and an outgoing fluid stream 442. The fluid flowsthrough a sterile fluid circuit as discussed earlier and can act tocontrol a temperature at one or more locations proximal to the flowingfluid. Those skilled in the art would appreciate a potential risk fromleakage of fluids into the larger imaging and treatment zone. Forexample, patient body fluids, e.g., urine, may inadvertently bedischarged and wet components of the imaging or treatment system. Also,a leak from a fluid coupling or from a rupture in a fluid tubing membercan also result in unwanted wetting or shorting of other components inthe treatment environment 40. This would be unfortunate in someinstances, depending on the amount of fluid leaked, the location of theleak, and the type of components that the leaked fluid comes intocontact with. In some cases a risk of electrical shorting or malfunctionor interference with the treatment or imaging system could be a concern.Therefore, it is the object of some features hereof to address suchfluid leaks if they were to occur.

In one embodiment, a fluid catchment member 420 is provided to catchfluids leaking from or around the treatment region and treatmentapparatus. The catchment member 420 may include a waterproof sheet ofmaterial 420, which is sized and positioned and formed so as to collectleaking fluid 430 so the leaking fluid does not drain into undesired orharmful locations. The catchment member 420 may be a flexible sheet ofdisposable spill-proof fabric that can be torn or dispensed from adispenser, e.g. on a roll, and later discarded as waste. The catchmentmember 420 may also be formed of a washable plastic or similar materialand formed by extrusion for example into a shallow tub that accommodatesthe patient and other equipment and collects any leaked fluid. Such leakcontrol systems can accommodate a relatively large amount of leakedfluid, and may be able with a suitable drain system as described belowto handle an arbitrary amount of leaked fluid.

In yet other embodiments, the catchment member 420 is made of anabsorbing material that can hold a substantial amount of fluid (e.g.,50, 250, 500 milliliters or more) if such a fluid 430 were spilled ontothe catchment member 420.

Catchment member 420 is optionally provided with a drainage channel 450which drains collected fluid from the catchment member 420 to acollection container or other non-harmful location. The drainage channel450 may be in the form of a clear (e.g., Tygon®) tube coupled suitablyto a low point of the catchment member 420. A pump or vacuum system maybe used to draw spilled fluid 430 from and through the drainage channel450. The drainage channel 450 may alternatively be formed as agutter-like channel that is open but still allows for gravity drainmovement of leaked fluid 430 away from the treatment zones and sensitiveequipment.

In some aspects, it is desirable to have an alarm or warning system toalert technicians or operators to fluid leaks. A moisture sensor,conduction meter, thermometer, fiber optic sensor, or other sensor canbe installed at one or more locations in the environment 40 so as tosense if and when a fluid leak has occurred. Upon sensing a leak analarm or warning signal is sent to a visible or audible alarm siren toalert the operator. The operator can then choose to interrupt thetreatment session to investigate it or take other action. A level sensoror float can be placed in a collection reservoir connected to thedrainage channel 450 to indicate a minimum accepted leakage in otherembodiments. In still other embodiments, pressure sensors in fluidcircuit 440-442 or at other locations in the fluid circuit can warn of aloss of pressure in the system, which may indicate a fluid leak orrupture in the system.

The present invention should not be considered limited to the particularembodiments described above. Various modifications, equivalentprocesses, as well as numerous structures to which the present inventionmay be applicable, will be readily apparent to those skilled in the artto which the present invention is directed upon review of the presentdisclosure.

1. A fluid control system for use in a thermal therapy system, the fluidcontrol system comprising: a volume for filling with a fluid, said fluidadapted for flow through a fluid circuit portion of said apparatus; apressure source that drives said fluid through said fluid circuit; aninlet portion of said fluid circuit that allows said fluid to pass intoa portion of said thermal therapy system; an outlet portion of saidfluid circuit that allows said fluid to pass out of said portion of saidthermal therapy system; a temperature sensor disposed between saidpressure source and said portion of the thermal therapy system, thatsenses a temperature of said fluid, or a temperature of a patient'stissue proximal to a position of said temperature sensor, and provides acorresponding temperature sensor output signal indicative of saidtemperature; a temperature controller that receives said temperaturesensor output signal and that receives a reference signal indicative ofa desired temperature setting, and that provides an output controlsignal; and a thermal element that receives said output control signaland that acts to change the quantity of heat energy in the fluid so asto maintain the temperature of said fluid substantially at or near thedesired temperature setting,
 2. The fluid control system of claim 1,further comprising fluid couplings that couple a first portion of saidsystem that lies within an imaging and treatment chamber from a secondportion of said system that lies outside said imaging and treatmentchamber.
 3. The fluid control system of claim 1, further comprising awarning circuit that senses an unwanted condition of said system anddelivers a warning signal corresponding to said condition.
 4. The fluidcontrol system of claim 3, said unwanted condition including atemperature that departs from said desired temperature setting.
 5. Thefluid control system of claim 3, said unwanted condition including apressure in said fluid circuit that departs from a desired pressuresetting.
 6. The fluid control system of claim 3, said unwanted conditionincluding a fluid leak.
 7. The fluid control system of claim 1, furthercomprising a fluid catchment member that collects any leaked fluid toavoid undesired spilling of said leaked fluid.
 8. The fluid controlsystem of claim 7, said catchment member comprising a spill-proofdisposable sheet.
 9. The fluid control system of claim 7, said catchmentmember comprising a plastic pan that collects any said leaked fluid. 10.The fluid control system of claim 7, said catchment member comprising anabsorptive material that absorbs and holds any said leaked fluid. 11.The fluid control system of claim 7, further comprising a drainagechannel for draining leaked fluid from the catchment member.
 12. Thefluid control system of claim 1, further comprising a second temperaturesensor that senses a temperature proximal to a second location of saidsecond sensor and provides a second temperature sensor output signal tosaid temperature controller.
 13. The fluid control system of claim 1,said heat element comprising an element that adds heat to said fluid soas to raise a temperature of said fluid.
 14. The fluid control system ofclaim 1, said heat element comprising an element that removes heat fromsaid fluid so as to lower a temperature of said fluid.
 15. The fluidcontrol system of claim 1, further comprising a gas removal member tode-gas said fluid within desired gas content limits.
 16. The fluidcontrol system of claim 1, said inlet portion providing a supply of saidfluid to a location in said thermal treatment system proximal to anultrasonic treatment applicator of the thermal therapy system to heat orcool a region of tissue of a patient undergoing thermal therapy, asneeded, and said outlet portion taking a return of said fluid from saidlocation in said thermal treatment system.
 17. A method for controllinga fluid in a prostate thermal therapy system, comprising: providing afluid in a fluid circuit; pumping said fluid, using a pump, through aninlet portion of the fluid circuit to a location in a thermal applicatorproximal to which thermal therapy is to be carried out; receiving areturn of said fluid from said location into a return portion of saidfluid circuit; measuring a temperature of said fluid, at a location insaid fluid circuit between said pump and said location where thermaltherapy is to be carried out, and generating a temperature sensingsignal corresponding to said temperature; comparing said temperaturesensing signal to a reference signal; and controlling a heat element toadd heat to said fluid if its temperature drops below a desired settingor to remove temperature from said fluid if its temperature rises abovesaid desired setting.
 19. The method of claim 18, further comprisingcollecting any fluid that may leak from said fluid circuit.
 20. Themethod of claim 18, further comprising sensing an undesired conditionwithin said fluid circuit.
 21. The method of claim 18, said measuringstep comprising measuring a temperature of said fluid at or near adischarge of said pump.
 22. The method of claim 18, further comprisingcarrying out MRI-based thermometry scans of said location where thethermal therapy is to be carried out to determine a temperature of atleast a portion of